Aims: The TARS randomised controlled trial evaluated the effectiveness of up to 8 weeks of health trainer support focused on increasing physical activity (PA) and reducing smoking on 6-month prolonged abstinence for smokers wishing to reduce but not quit. Here we examine the intervention effects on behaviour change process-related survey measures.
Methods: Participants (N=915) in Plymouth, London, Oxford, and Nottingham were randomised to intervention (n=457) or control (n=458). Questionnaire data were collected at baseline and 3 months (5-point Likert scale – strongly agree to strongly disagree) related to self-reported confidence and importance for reducing and quitting smoking (and for increasing PA), action and coping planning for smoking reduction (and increasing PA), urges to smoke, social support, and using PA as a way of controlling smoking. Data were analysed comparing change from baseline to 3 months between intervention and control using a multi-variable linear regression model controlling for baseline score and pre-specified variables.
Results: The intervention had significant positive effects on 10 (out of 11) smoking-related psychological measures (p<0.001) and five (out of seven) PA measures (p<0.01), including using PA as a way to control smoking behaviour (p=0.001). Importance of quitting, importance of PA, and a measure of social support for PA were the only measures that showed no significant effects (p>0.05). Conclusions: Behavioural support to increase PA and reduce smoking had positive effects on most measures of behaviour change processes linked to the intervention logic model over 3 months, which supports their causal role in reducing smoking and increasing PA.